Thanks for the advice. I would use some higher end servos but I unfortunately don't have the budget. The gun I'll be using is a light-weight airsoft gun, I'll also be spending lots of front end time minimizing the inertia of the system. I think at least for my prototype some high-torque hobby servo motors should work, I just need to know how accurate they will be and how I can maximize their accuracy. These guys have been building something similar to what I'm trying to do and they seem to be doing well with just hobby servos - http://paintballsentry.com.